Bottom Line:
MRI studies demonstrate that structural changes in frontal cortex are associated with functional abnormalities in Internet addicted subjects.Nuclear imaging findings indicate that IA is associated with dysfunction of the brain dopaminergic systems.Further investigations are needed to determine specific changes in the Internet addictive brain, as well as their implications for behavior and cognition.

ABSTRACTMaladaptive use of the Internet results in Internet addiction (IA), which is associated with various negative consequences. Molecular and functional imaging techniques have been increasingly used for analysis of neurobiological changes and neurochemical correlates of IA. This review summarizes molecular and functional imaging findings on neurobiological mechanisms of IA, focusing on magnetic resonance imaging (MRI) and nuclear imaging modalities including positron emission tomography (PET) and single photon emission computed tomography (SPECT). MRI studies demonstrate that structural changes in frontal cortex are associated with functional abnormalities in Internet addicted subjects. Nuclear imaging findings indicate that IA is associated with dysfunction of the brain dopaminergic systems. Abnormal dopamine regulation of the prefrontal cortex (PFC) could underlie the enhanced motivational value and uncontrolled behavior over Internet overuse in addicted subjects. Further investigations are needed to determine specific changes in the Internet addictive brain, as well as their implications for behavior and cognition.

fig1: Cortical thickness differences in adolescents with IGD compared with healthy controls. Increased cortical thickness was observed in several regions in adolescents with IGD compared to healthy controls, that is, the left precentral cortex, precuneus, middle frontal cortex, and inferior temporal and middle temporal cortices. Reduced cortical thickness in the left lateral OFC, insula cortex, and lingual gyrus, along with the right postcentral gyrus, entorhinal cortex, and inferior parietal cortex were detected in adolescents with IGD [23].

Mentions:
Using MRI, some studies have shown that brain structural changes are associated with IA. Using the Stroop color-word test [22], which has been widely used for assessing inhibitory control, a study reported that adolescents with IGD showed impaired cognitive control ability [23]. Imaging results demonstrated that brain regions associated with executive function, for example, the left lateral orbitofrontal cortex (OFC), insula cortex, and entorhinal cortex, showed decreased cortical thickness in IGD subjects compared with controls (Figure 1). Moreover, the authors also reported that the reduced cortical thickness of the left lateral OFC was correlated with the impaired cognitive control ability in IGD adolescents. Consistent with this, another study also reported reduced thickness in the OFC of Internet addicted adolescents [24]. Given the view that the OFC is implicated in the pathology of drug and behavioral addictions [25, 26], the authors suggest that IA shares similar neurobiological mechanism with other addictions. Apart from the decreased cortical thickness, increased cortical thickness was also observed in the left precentral cortex, precuneus, middle frontal cortex, and inferior temporal and middle temporal cortices [23] (Figure 1). The precuneus is associated with visual imagery, attention, and memory retrievals [27]. The inferior temporal cortex and the middle frontal cortex have been shown to engage in craving induced by drug cues [28, 29]. Therefore, these results suggest that the increased cortical thickness areas in IGD may be associated with craving of gaming cues.

fig1: Cortical thickness differences in adolescents with IGD compared with healthy controls. Increased cortical thickness was observed in several regions in adolescents with IGD compared to healthy controls, that is, the left precentral cortex, precuneus, middle frontal cortex, and inferior temporal and middle temporal cortices. Reduced cortical thickness in the left lateral OFC, insula cortex, and lingual gyrus, along with the right postcentral gyrus, entorhinal cortex, and inferior parietal cortex were detected in adolescents with IGD [23].

Mentions:
Using MRI, some studies have shown that brain structural changes are associated with IA. Using the Stroop color-word test [22], which has been widely used for assessing inhibitory control, a study reported that adolescents with IGD showed impaired cognitive control ability [23]. Imaging results demonstrated that brain regions associated with executive function, for example, the left lateral orbitofrontal cortex (OFC), insula cortex, and entorhinal cortex, showed decreased cortical thickness in IGD subjects compared with controls (Figure 1). Moreover, the authors also reported that the reduced cortical thickness of the left lateral OFC was correlated with the impaired cognitive control ability in IGD adolescents. Consistent with this, another study also reported reduced thickness in the OFC of Internet addicted adolescents [24]. Given the view that the OFC is implicated in the pathology of drug and behavioral addictions [25, 26], the authors suggest that IA shares similar neurobiological mechanism with other addictions. Apart from the decreased cortical thickness, increased cortical thickness was also observed in the left precentral cortex, precuneus, middle frontal cortex, and inferior temporal and middle temporal cortices [23] (Figure 1). The precuneus is associated with visual imagery, attention, and memory retrievals [27]. The inferior temporal cortex and the middle frontal cortex have been shown to engage in craving induced by drug cues [28, 29]. Therefore, these results suggest that the increased cortical thickness areas in IGD may be associated with craving of gaming cues.

Bottom Line:
MRI studies demonstrate that structural changes in frontal cortex are associated with functional abnormalities in Internet addicted subjects.Nuclear imaging findings indicate that IA is associated with dysfunction of the brain dopaminergic systems.Further investigations are needed to determine specific changes in the Internet addictive brain, as well as their implications for behavior and cognition.

ABSTRACTMaladaptive use of the Internet results in Internet addiction (IA), which is associated with various negative consequences. Molecular and functional imaging techniques have been increasingly used for analysis of neurobiological changes and neurochemical correlates of IA. This review summarizes molecular and functional imaging findings on neurobiological mechanisms of IA, focusing on magnetic resonance imaging (MRI) and nuclear imaging modalities including positron emission tomography (PET) and single photon emission computed tomography (SPECT). MRI studies demonstrate that structural changes in frontal cortex are associated with functional abnormalities in Internet addicted subjects. Nuclear imaging findings indicate that IA is associated with dysfunction of the brain dopaminergic systems. Abnormal dopamine regulation of the prefrontal cortex (PFC) could underlie the enhanced motivational value and uncontrolled behavior over Internet overuse in addicted subjects. Further investigations are needed to determine specific changes in the Internet addictive brain, as well as their implications for behavior and cognition.